An array speaker apparatus outputting a sound beam having a directivity by delaying audio signals and distributing the delayed audio signals to a plurality of speaker units is conventionally known (see Patent Document 1).
In the array speaker apparatus of Patent Document 1, a sound source is localized by making a sound beam of each channel reflected on a wall to reach a listener from around the listener.
Besides, in the array speaker apparatus of Patent Document 1, with respect to a channel whose sound beam cannot reach the listener due to, for example, the shape of the room, filtering processing based on a head-related transfer function is carried out for performing processing for localizing a virtual sound source.
More specifically, in the array speaker apparatus described in Patent Document 1, a head-related transfer function corresponding to the head shape of a listener is convolved to an audio signal for changing the frequency characteristic. The listener perceives a virtual sound source by hearing a sound whose frequency characteristic has been thus changed (a sound for making a virtual sound source perceived). Thus, the audio signal is virtually localized.
Besides, another array speaker apparatus outputting a sound beam having a directivity by delaying audio signals and distributing the delayed audio signals to a plurality of speaker units is known (see, for example, Patent Documents 2 and 3).
In an array speaker apparatus of Patent Document 2, a sound beam of a C channel and a sound beam reaching a listener after being reflected on a wall are used for outputting the same signal at a prescribed ratio, so as to localize a phantom sound source. A phantom sound source means a virtual sound source localized, when sounds of the same channel are allowed to reach a listener from right and left different directions, in a middle direction between these different directions.
Furthermore, in an array speaker apparatus of Patent Document 3, a sound beam having been reflected once on a wall disposed on the right or left side of a listener and a sound beam having been reflected twice on walls disposed on the right or left side and behind the listener are used for localizing a phantom sound source in the middle between a localization direction of a front channel and the localization direction of a surround channel.